This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Peter DiMaria RNA Cap Hypermethylases in Microsporidia Microsporidia are primitive one-celled parasitic organisms which infect a wide range of species including humans. A number of microsporidial species are responsible for serious diseases in AIDS patients and other individuals with compromised immune systems. With regard to certain cellular molecules, the microsporidia are very different from other organisms. These differences could be exploited towards the development of anti-infective treatment of afflicted patients. The project concerns certain microsporidial enzymes responsible for attaching methyl groups onto structures known as RNA caps. RNA caps are attached on the ends of certain RNA molecules and direct their movement inside of cells. The structure of the RNA caps associated with microsoporidial RNAs appears to differ markedly from those seen in other organisms with respect to the number of attached methyl groups. The microsporidial enzymes responsible for adding the methyl groups to the caps are likely to be different from the corresponding enzymes in other organisms. The work will first seek to identify the microsporidial genes that encode these enzymes. The genes will then be introduced into bacteria. There, the genes will express the encoded proteins. The expressed proteins will be extracted from the bacteria and purified. They will then be assessed for their ability to attach methyl groups to RNA caps. The detailed molecular and catalytic properties of these enzymes will also be studied. Overall, the project is expected to yield valuable information on these novel microsporidial enzymes.